How to know battery going to be flat?

[Kb27]

http://www.straitstimes.com/lifestyle/torque-shop-12

 

 

The best way to check a battery's condition is to measure the voltage across the terminals while cranking the engine. Anything less than 12 volts indicates that the battery is nearing the end of its life.

At rest, the battery voltage should read between 13 and 14 volts, even though the battery is specified as a 12-volt DC power supply.

As you correctly pointed out, most cars do not feature a voltmeter, so the only means to check the condition of the battery is to have the voltage measured by a battery shop.

Almost all of them are equipped with a simple instrument to measure voltage. While you are at it, ensure that your car battery's voltage is no less than 13.5 volts during idling. With higher revs, the battery voltage should rise to at least 14.4 volts. This will tell you if the alternator is performing well.

 

 

There are multiple errors in this article.

 

1. Yes, you can check crank voltage - that means measuring the voltage across the battery terminal while you're cranking, before the engine started. Anything less than 12V indicates battery end of life is NOT TRUE. Crank voltage must be at least 9.7V and above, not 12V. Unless it's super-duper overly heavy sized battery that can withstand the crank and still hold out at 12V. Most normal sized, good battery will drop to about 10~11V during crank.

 

The next problem is even a normal multimeter is not capable of reading the crank voltage, as it is TOO FAST (less than a second before the engine starts). You need a specialized meter to catch that low crank voltage.

 

2. At rest (without the engine/alternator running), the battery voltage does not read between 13~14V. It reads max of 12.6V. Nominal battery voltage is 12V, but it's actually around 12.6V when fully charged. It may read 13~14V just after shutting down the engine, for a short while. This is due to the surface charge caused by the alternator charging at 14V. After a couple of min or hrs, the charge disappears and the battery voltage drops back to 12.6V (fully charged)

 

3. Another error is to say 13.5V during idling and 14.4V when revving. This is actually a sign of a defective alternator.

A good alternator keeps the voltage range variation to a min. That means, if the battery terminal or alternator measures 13.5V during idling, it must also keep to around 13.5V during high rev. This is a function of the voltage regulator inside the alternator. It regulates voltage and keeps them to around the same during both idling and high rev.

 

If the voltage regulator is defective, then yes, during idling the voltage is low, sometimes around 13V only and when you rev, it goes up to 14.4V. This defective voltage regulator eventually leads to poor charging of the battery (deficit charge) and you'll not be able to crank start your engine one day. But that's not the fault of the battery, but the fault of the alternator.

 

Another thing about alternator is that each car is different. Some charge with 13.3V only, some charge with 14.4V. It doesn't mean 14.4V is superior. It has its own advantage/disadvantage. And many advanced cars now comes with voltage regulation controlled by ECU. It starts off low at 13V and rising to 14V typically. So without knowing what kind of regulatory controls, you can't simply point to voltage and say what is good and what is bad.

 

So, whoever wrote this article is really ill-informed.

Edited September 16, 2017 by Kb27

[Mkl22]

There are multiple errors in this article.

 

1. Yes, you can check crank voltage - that means measuring the voltage across the battery terminal while you're cranking, before the engine started. Anything less than 12V indicates battery end of life is NOT TRUE. Crank voltage must be at least 9.7V and above, not 12V. Unless it's super-duper overly heavy sized battery that can withstand the crank and still hold out at 12V. Most normal sized, good battery will drop to about 10~11V during crank.

 

The next problem is even a normal multimeter is not capable of reading the crank voltage, as it is TOO FAST (less than a second before the engine starts). You need a specialized meter to catch that low crank voltage.

 

2. At rest (without the engine/alternator running), the battery voltage does not read between 13~14V. It reads max of 12.6V. Nominal battery voltage is 12V, but it's actually around 12.6V when fully charged. It may read 13~14V just after shutting down the engine, for a short while. This is due to the surface charge caused by the alternator charging at 14V. After a couple of min or hrs, the charge disappears and the battery voltage drops back to 12.6V (fully charged)

 

3. Another error is to say 13.5V during idling and 14.4V when revving. This is actually a sign of a defective alternator.

A good alternator keeps the voltage range variation to a min. That means, if the battery terminal or alternator measures 13.5V during idling, it must also keep to around 13.5V during high rev. This is a function of the voltage regulator inside the alternator. It regulates voltage and keeps them to around the same during both idling and high rev.

 

If the voltage regulator is defective, then yes, during idling the voltage is low, sometimes around 13V only and when you rev, it goes up to 14.4V. This defective voltage regulator eventually leads to poor charging of the battery (deficit charge) and you'll not be able to crank start your engine one day. But that's not the fault of the battery, but the fault of the alternator.

 

Another thing about alternator is that each car is different. Some charge with 13.3V only, some charge with 14.4V. It doesn't mean 14.4V is superior. It has its own advantage/disadvantage. And many advanced cars now comes with voltage regulation controlled by ECU. It starts off low at 13V and rising to 14V typically. So without knowing what kind of regulatory controls, you can't simply point to voltage and say what is good and what is bad.

 

So, whoever wrote this article is really ill-informed.

Wanted to praise you but can't. Kb27 explained it all

[Hamburger]

If one cranked and gets a 12v reading, it's not a battery.

 

It's a power station.

[Gnahp]

Yup. You are Absolutely correct.

 

I should email mr changaroth the battery FAQ!!!

 

That's why I refuse to ever bother with local motoring journalist! Crock of crap they spout!

many "high hand" in this forum, bro kb27 is one of them

 

I pity those newbies who wanted to learn a thing or two about their car

 

wanted to know how to go Tampines and got pointed to Jurong

 

some eventually make it to Tampines and most still stuck and lost in Jurong

[therock]

There are multiple errors in this article.

 

1. Yes, you can check crank voltage - that means measuring the voltage across the battery terminal while you're cranking, before the engine started. Anything less than 12V indicates battery end of life is NOT TRUE. Crank voltage must be at least 9.7V and above, not 12V. Unless it's super-duper overly heavy sized battery that can withstand the crank and still hold out at 12V. Most normal sized, good battery will drop to about 10~11V during crank.

 

The next problem is even a normal multimeter is not capable of reading the crank voltage, as it is TOO FAST (less than a second before the engine starts). You need a specialized meter to catch that low crank voltage.

 

2. At rest (without the engine/alternator running), the battery voltage does not read between 13~14V. It reads max of 12.6V. Nominal battery voltage is 12V, but it's actually around 12.6V when fully charged. It may read 13~14V just after shutting down the engine, for a short while. This is due to the surface charge caused by the alternator charging at 14V. After a couple of min or hrs, the charge disappears and the battery voltage drops back to 12.6V (fully charged)

 

3. Another error is to say 13.5V during idling and 14.4V when revving. This is actually a sign of a defective alternator.

A good alternator keeps the voltage range variation to a min. That means, if the battery terminal or alternator measures 13.5V during idling, it must also keep to around 13.5V during high rev. This is a function of the voltage regulator inside the alternator. It regulates voltage and keeps them to around the same during both idling and high rev.

 

If the voltage regulator is defective, then yes, during idling the voltage is low, sometimes around 13V only and when you rev, it goes up to 14.4V. This defective voltage regulator eventually leads to poor charging of the battery (deficit charge) and you'll not be able to crank start your engine one day. But that's not the fault of the battery, but the fault of the alternator.

 

Another thing about alternator is that each car is different. Some charge with 13.3V only, some charge with 14.4V. It doesn't mean 14.4V is superior. It has its own advantage/disadvantage. And many advanced cars now comes with voltage regulation controlled by ECU. It starts off low at 13V and rising to 14V typically. So without knowing what kind of regulatory controls, you can't simply point to voltage and say what is good and what is bad.

 

So, whoever wrote this article is really ill-informed.

You certainly are the pro on batteries..

 

I wrote an email to Christopher Tan, so he can pass it onto the person who wrote it..

 

 

[Axela525]

You certainly are the pro on batteries..

 

I wrote an email to Christopher Tan, so he can pass it onto the person who wrote it..

But I only want to know Mazda 3...the istop will be orange?

Edited September 16, 2017 by Axela525

[Lotr8445r]

Got link boh?

I also want to buy.

TIA

It is similar like that:

 

https://m.aliexpress.com/price/display-voltmeter-battery_price.html#/

[neski]

Got link boh?

I also want to buy.

TIA

 

 

Check this out, can use as a USB charger as well--

 

 

https://detail.tmall.com/item.htm?id=44469678973&ali_refid=a3_430008_1006:1104073449:N:车载充电器:a5d419393beac7251422524022d7fc88&ali_trackid=1_a5d419393beac7251422524022d7fc88&spm=a230r.1.0.0.76bf5235fw716

 

 

Edited September 16, 2017 by neski

[Kklee]

Check this out, can use as a USB charger as well--

 

 

https://detail.tmall.com/item.htm?id=44469678973&ali_refid=a3_430008_1006:1104073449:N:车载充电器:a5d419393beac7251422524022d7fc88&ali_trackid=1_a5d419393beac7251422524022d7fc88&spm=a230r.1.0.0.76bf5235fw716

 

There is a voltage drop is measurement is taken from the cigarette lighter socket. 

[ER-3682]

But I only want to know Mazda 3...the istop will be orange?

For Mazda 6 Pre FL 2.5 will have Message...

[Terrylmt]

If one cranked and gets a 12v reading, it's not a battery.

 

It's a power station.

I could be mistaken, but i remember reading somewhere that BMWs need 12.1V to start engine. That's why they need bigger batteries. Just sharing.

[S0n1c]

Having a voltage is the best to tell where your battery is dying before it died halfway when u abt to head out or already outside.

[Hamburger]

Google translated England.

[Jamesc]

Since COE is 10 years.

 

I just change every 2.5 years.

 

 

[Watwheels]

How many times ppl got to mention it's the CCA rating that matters?

https://www.google.com.sg/search?q=ideal+cold+crank+amp&ie=utf-8&oe=utf-8&client=firefox-b&gfe_rd=cr&dcr=0&ei=hQ_gWZf4OK6IX5avkagL

 

CCA is a rating used in the battery industry to define a battery's ability to start an engine in cold temperatures. The rating refers to the number of amps a 12-volt battery can deliver at 0°F for 30 seconds while maintaining a voltage of at least 7.2 volts.

 

You gotta have a device like this...called th battery analyzer.

 

 

It's not a cheap device. It costs around $200+ to $300. You can get this from online shops but no point coz when the battery fails this thing cannot save it. It can only tell you good or bad. It doesn't advise you when to change your car battery.

[Kb27]

I could be mistaken, but i remember reading somewhere that BMWs need 12.1V to start engine. That's why they need bigger batteries. Just sharing.

 

Not just BMW, all cars need power to start.

Voltage like 12.1V is just the state of charge of the battery.

So any battery that is charged have a voltage ranging from 12.1 (low charged) to 12.7V (fully charged)

Power to start requires current.

Current to start may be anywhere from 150A to 200A and the battery must be able to provide it.

It can't provide that current when it's discharged (below 12V), like those who put dashcam and discharged it overnight.

 

If you have a bad battery, it can still read 12.6V, but fail to crank the engine.

 

You can have a small lithium jump starting battery or a good 35AH battery and still start a BMW.

There's nothing special.

 

Actually the battery is just for turning over the engine.

Starting the engine requires, compression, petrol and air, which is not the function of the battery.

 

So, the answer is even putting a small 35AH battery on a BMW will work, to start its engine.

[Mcf777]

Yesterday, my car have weak cranking.

Immediately drove to battery shop and change it.

Amaron battery, lasted me for two years.

 

the battery connector broke into half and full of greenish powder on it. Lucky no short circuit.

 

Changed the same brand 80ah. I think called hi life pro.

S$160 for the battery.

Edited October 13, 2017 by Mcf777

[Kklee]

How many times ppl got to mention it's the CCA rating that matters?

https://www.google.com.sg/search?q=ideal+cold+crank+amp&ie=utf-8&oe=utf-8&client=firefox-b&gfe_rd=cr&dcr=0&ei=hQ_gWZf4OK6IX5avkagL

 

You gotta have a device like this...called th battery analyzer.

 

 

It's not a cheap device. It costs around $200+ to $300. You can get this from online shops but no point coz when the battery fails this thing cannot save it. It can only tell you good or bad. It doesn't advise you when to change your car battery.

 

Aliexpress below SGD100.

If SOH is State of Health,   the % may give an indication of the health of the battery.

Alternatively,  the A and internal resistance may also give an indication but reference needs to be taken when the battery is new or known to be good.   

E.g.  if SOH is at 50%,  you have to decide if want to change.  Likely I may wait until 25%.  

Yesterday, my car have weak cranking.

Immediately drove to battery shop and change it.

Amaron battery, lasted me for two years.

 

the battery connector broke into half and full of greenish powder on it. Lucky no short circuit.

 

Changed the same brand 80ah. I think called hi life pro.

S$160 for the battery.

 

Just curious, the sidewalls of the old battery got become bloated? 

Edited October 13, 2017 by Kklee